This invention relates to cutting apparatus and, in particular, to apparatus for cutting keys.
For purposes of illustration, this invention will be described in connection with coded key cutting machines as are described in U.S. Pat. Nos. 4,019,415 and 3,981,214. These key cutters utilize a reciprocating punch and die mechanism to cut notches in a key blank. The key blank is secured within the jaws of a vise, and the punch and die are moved along the operative edge of the key blank by a slide mechanism. The depth of the notches is controlled by means of moving the vise perpendicularly towards or away from the direction of the sliding punch and die. The notches are cut at standard notch locations along the length of the key based upon an analysis of a sample key or information obtained from the manufacturer of the lock. Since the sample key is only used to determine the desired standard depth of the notch to be made, rather than acting as a pattern for the cut, the inaccuracies of the sample are not transferred to the new key.
The precision of these cutting apparatus is, to a large extent, dependent on the precise alignment of the vise holding the key blank and the die. Unless the key blank is supported by the top surface of the die during the cutting process, the force exerted on the key by the punch will cause the key to bend, distorting the notches. On the other hand, if the die is too high, the friction of the key against the die will prevent the proper operation of the apparatus' slide mechanism. As a result, the manufacture of the apparatus is difficult due to the exacting tolerances which must be maintained to achieve this alignment. In addition, over time, the repeated exertion of force on the die during the cutting operation results in a certain amount of "play" being introduced into the slide mechanism of the punch and die holder causing the attendant potential for misalignment of the die and the vise.
Most keys incorporate at least one groove along one of their edges. Many keys are varied in thickness or include a step between this grooved portion and their notched or operative edge. The spacing of these grooves and the size of the step varies widely from manufacturer to manufacturer. As a result, the desired alignment between the die and vise of the apparatus changes depending on the manufacturer of the key being cut. Unfortunately, the cutting apparatus generally needs to be substantially dismantled to adjust this alignment.
Not only do key thicknesses and steps vary from manufacturer to manufacturer, however, but the shapes of the notches vary as well. As a result, when switching from cutting one manufacturer's key to another's, one must often replace the punch and die of the cutting apparatus. This too generally necessitates the substantial dismantling of the cutting apparatus. Due to the inconvenience of this procedure, it is common practice to purchase a number of coded key cutting machines to avoid the inconvenience and delay of changing punches.
Coded key cutting apparatus offer significant advantages in its simplicity, affordability and portability. There is needed, however, a durable key cutting apparatus for which the difficulties of aligning the vise and the die are minimized, and the quick and easy replacement of the punch and die is facilitated.